Nanocrystalline manganese oxides have been gaining importance in the fields of catalysis, electrochemistry, ion-exchange materials, magnetite, sensors, batteries, etc. An in - situ sol-gel process is investigated to synthesize uniform dispersion of the Mn2O3 nanocrystals in silica matrix for the formation of Mn2O3/SiO2 nanocomposite. The sample of composition 10% Mn2O3 - 90% SiO2 was prepared by sonicating required amount of TEOS, ethanol and distilled water for 10 minutes and 10 ml of ammonium solution was added as a base catalyst. Manganese acetate dissolved in 10 ml of ethylene glycol was added to TEOS solution and sonicated further for 10 min to form a clear gel. The obtained gel was dried and heated from 473 to 1173 K. TG-DTA curve of the heated sample showed the decomposition temperature and elements. XRD patterns of sample heated at 1173 K confirmed the formation of Mn2O3 nanocrystalline phase in amorphous SiO2 matrix and the calculated crystallite size is found to be ~30 nm. FTIR spectra of the sample heated from 373 to 1173 K revealed the formation of Mn2O3 structure in SiO2 matrix. The XRD and FTIR results confirmed the formation of Mn2O3 nanocrystals in the SiO2 amorphous matrix, which forms Mn2O3/SiO2 nanocomposite.